MULTILAYER COEXTRUDED FILM FOR PARENTERAL SOLUTIONS BAGS

Abstract: A cast-coextruded film for sterilizable, low extractable containers of parenteral solutions, which is flexible, transparent, heat-sealable, free from aromatic adhesive, incinerable without fumes, consists at least of: a layer of polyamide, a layer essentially of LLDPE, and a polymeric adhesive layer of ethylene polymer or copolymer.

Description: Title: Multilayer coextruded film for parenterai solutions bags. DESCRIPTION The present invention concern flexible, transparent multilayer coextruded films, on one layer of which can be possibly laminated further layers. More particularly the invention concerns a coextruded multilayer film for sterilizable, low extractable containers of parenterai solutions, said film being; flexible and trasparent before and after steam sterilization, heatseable to itself and/or to the parenterai solution container access ports by its inner or outer layer: free from aromatic adhesive, incinerable without release of halogen containing fumes; and comprising at least a layer of olefin (co-) polymers and a layer of amide (co-) polymer. The wide diffusion of plastic containes (bags, pouches) for parenterai solutions is known; consequently also the requirement of having films adequate to this purpose is known. PRIOR ART The Prior Art has suggested a lot of flexible films comprising layers of polyamide (PA) and of polyethylene (PE), all certainly interesting however not free of inconveniences. In particular US Patent N° ^,326,574- describes flexible bags made of laminates consisting of an outer layer of polypropylene (PP), an inner layer of polyethylene (PE) (in this case a polymer sustantially of ethylene units combined with a minor proportion of butylene units), and of a central layer of polyamide (PA). The film is obtained by lamination with the aid of a polyurethane adhesise which can, in case, decompose and/or migrate into the solution during and after steam sterilization. All attempts to reproduce such a structure by coextrusion failed: the blown coextruded PP-PA-PE had unacceptable transparency whereas the cast coextrudates could be obtained only with a PE-copoiymer of very low molecular weight which was however not sterilizable in autoclave. European Patents N° 15775 and 11° 10273S, and US Patents N° 3,791,915 and N° 33973S2 describe several solutions which for one or the other reason do not appear to have had the hoped success. It has now been found (not without surprise) that the inconveniences present in the Prior Art, either in the phase of the film coextrusion or in the phase of form-and filling and sterilization of the bags, are eliminated with the coextruded film according to the invention which arecharacterized by at least three layers: A) an outer layer having a thickness of from 10-60 preferably 15 to 50 microns and consisting of one or more polya ides (PA); B) an inner layer having a thickness of from 60 to 150 preferably from 80 to 130 microns, consisting of a linear low density (co-) polymer of ethylene (LLDPE) with a minor proportion from 0,5 to 10% of an alfa-olefin containing from to 12 carbon atoms, or of a blend of this (co-) polymer with from 5 to 25% of a low density polyethylene (LDPE), and containing from 0,1 -3% of a slip agent; C) a polymer adhesive intermediate layer having a thickness of from 3 to 20 microns and consisting of polyethylene (s) or ethylene copolymers with vin\l acetate (EVA), grafted with from 0.1 to 0,7% of maleic anhydride. In one embodiment particularly advantageous, two further layers D) and E) are provided by coextrusion on the polyamidic layer A), the layer D) whith a thickness of from 3 to 5 microns consisting of polyethylene or polypropylene treated with maleic anhydride and the layer E) with a thickness of from 20 to 60 microns consisting of a statistic (co-) polymer of propyiene or of polyethylene. In an other embodiment the layer D) is laminated on the polyamidie layer with a polvurethanic adhesive layer with a thickness of from 2 to 10 micron. From these fully coextruded or coextruded-laminated films according to the invention, pouches were prepared showing high characteristics of seal strength, softness, transparency, weldability and tensile strength. Characteristically the adhesive resin between the polyamide (PA) layer A) and the polyethylene (PE)layer B) is preferably selected from the group of polyethylene (s) (LLDPE or LPDE) containing 0,1 - 0,7% of maleic anhydride (AM) whereas the resin between the layers A) (PA) and E) (PP) is polypropylene with 0,1 - 0,5% maleic anhydride. For bags up to three liters of parenterai solution the preferred thickness and composition of the film according to the in.ention are as follows: layer composition thickness, micron preferred thickness A PA 10-50 15-35 B PE 60-150 b0-130 C LDPE or LLDPE 0,1-0,7% AM 5-20 7 - l 5 adhesives or D PP 0,1-0,5% AM 3-20 7-15 E PP 20-100 15--+0 The further features and advantages of the invention will better appear from the examples describing the embodiments schematically represented in the drawing in which Figure 3 shows an open pouch SA sealed on the edges LA and provided with a valve VA. Figure 1 shows the basic coextrudate with three layers A) (PA), B) (PE) and C) (adhesive) formed of polyethylene PE grafted with maleic anhydride (AM): and Figure 2 shows the relevant coextrudated/laminated of 5 layers i. e. with the addition of layers D') (adhesive = Polyurethane, PU) and E) (PP): and Figure 2a shows the fullv coextrudated 5 layers Film formed of the basic 3 layers (A-C-B) structure of Fig. 1, and of the additional two coextruded layers D) and E) consisting respectivalv of maleic anhydride grafted polypropylene (PP.AM), and of polypropv lene (PP). Description of the preferred embodiments The examples 1 - 6 below illustrate the preferred (but not limitative) embodiments. Ranges of thickness (in microns) for containers up to 3 liters A (PA) 10-5 B (PE) 60-150 C (Polvmeric adhesive) 5-20 D (Polymeric adhesive) 5-20 E (PP) 10-50 Example 1 A multilayer structure (ABC) containing 3 layers (Fig . 1) : The outer layer (A) consists of 30 microns polyamide-6 from EMS (grade XE 3314); the inner layer (B) consists of 1 10 microns of Cg-LLDPE from DSM (grade Stamylex 1046) additivated with 500 ppm of Erucamide slip agent ( 1% masterbatch Polybatch slip FSU 105 E of Schulman); the adhesive layer (C) consists of 10 microns of a 1 1 blend of 2 low density polyethylenes (LDPE) grafted with about 1.8% maleic anhydride such as those of DUPONT Bynel 402 and 408 This coextruded structure was used to fabricate one liter pouches on a form-fill-seal (FFS) machine at 25 bags/minute, which were sterilized at 1 18°C. exhibited low extractables, good transparency and were leak free The same structure was also gravure printed on the polyamide (PA) side (A) and then was laminated with a cast film consisting of random propylene-ethylene copolymer such as MOPLEN EP 1X35F of HIMONT having a thickness of 50 microns (layer E*), the adhesive layer (D 1 ) between the coextruded structure (A-B-C and layer (E 1 ) was a conventional two components polyurethane glue with a coating weight dry matter of 3 gr /m 2 The resulting semi-coext date/ laminate film (Fig. 2) was processed throu the same FFS machine to obtain leak free parenterai containers that exhibited excellent transparency and low extractables Film processing conditions The above structure A B C was produced on a REIFENHAUSER COMPACT cast coextrusion line for multilayer sheet film Line output 200 kg/hour Chill roll temperature 38°C - 40°C on PA side Winding speed 13 5 m/min Air knife combined with air suction under the die Feedblock 265°C Die 1 5 meter wide - 272° to 274°C • PA extruder screw diameter 70 mm output 55 kg/hr RPM 28 Barrel temperature 245 to 260°C Filter 260°C • PE extruder screw diameter 90 mm output 120 kg hr RPM 40 Barrel temperature 165 to 210°C Filter temperature 200°C Polymeric adhesive extruder screw diameter 50 mm output. 15 kg/hr RPM. 40 Barrel temperature 165°C to 210°C Filter temperature 200°C Table 1: semi-coex and semi-coex laminate properties (Example 1) Note: (a) semi-coex / laminate before sterilization (b) semi-coex / laminate after sterilization (c) semi-coex / before lamination after sterilization Example 2 A 3 layers structure consisting of: The outer layer (A) consists of 30 microns of a 20/80 blend of copolyamide PA^ /i2 - PA< of respective grades EMS XE 3303 and EMS XE 3180. ( * ) The inner layer (B) consists of 100 microns of C 8 ~ LLDPE - DOWLEX SC 2100 additivated with 500 ppm slip agent (1% masterbatch FSU 105 E or Schulman). The adhesive layer (C) consists of 10 microns of grafted LLDPE YPAREX 8104E from DSM . *) C8-LLDPE indicates linear low density polyetylene contai¬ ning octene ; (**) E means Erucamide . The processing conditions and film properties are comparable to those of the structure (c) of Example 1 Example 3 A 3 layers structure consisting of: The outer layer (A) consists of 30 microns of polyamide-6 from EMS - grade XE 3 180 The inner layer (B) consists of 1 10 microns of a 80/20 blend of Cg LLDPE from DSM (grade Stamylex 1026) and LDPE from Exxon (grade Escoreme LD 100 AG) additivated with 500 ppm slip agent ( 1% masterbatch FSU 105 E = Erucamide) The adhesive layer (C) consists of 10 microns of maleic anhydride grafted LLDPE from MITSUI (grade ADMER NF 530 E). The processing conditions and film properties are similar to those of the structure (c) of Example 1 Example 4 A fully coextruded 5 layers film (figure 2a) A five layers structure(EDACB) consisting of a core layer (A) consisting of 30 microns of polyamide 6 from EMS (grade XE 3180); an inner layer (B) consisting of 100 microns of Cg LLDPE from DSM (grade Stamylex 1026) additivated with 500 ppm Erucamide slip agent ( 1% masterbatch Polybatch slip FSU 105 E of Schulman); a polymeric adhesive layer (C) between layer (A) and (B), consisting of 8 microns of maleic anhydride grafted LLDPE YPAREX 8104 E from DSM; an outer layer (E) of 35 microns of ethylene-propylene random copolymer from PCD - DAPLEN KFC 2206SB; a polymeric adhesive layer (D) consisting of 10 microns of maleic anhydride grafted polypropylene (PP) from ATO (grade OREVAC PP-FT), between layers (A) and (E). Film processing conditions The line on which the structure was produced is the same as on Example 1 Total output 200 kg/hour Chill roll temperature 38°C - 40°C on the LLDPE side Winding speed 13 5 m/min Air knife combined with air suction under the die Feedblock temperature 265°C Die 1 5 meter wide - 271 °C to 274°C PA extruder screw diameter 50 mm output 35 kg/hr RPM 55 Barrel temperature 235°C to 250°C Filter 248°C • PP extruder screw diameter 90 mm output 35 kg/hr RPM 20 Barrel temperature 210°C to 242°C Filter temperature 240°C • LLDPE extruder screw diameter 70 mm output HO kg/hr RPM 70 Barrel temperature 200°C to 240°C Filter temperature 250°C • PP adhesive extruder screw diameter 50 mm output lO kg/hr RPM 38 Barrel temperature 190°C to 220°C Filter temperature 220°C PE adhesive extruder screw diameter 50 mm output lO kg/hr RPM 27 Barrel temperature 190°C to 225°C Filter temperature 230°C Table 2: 5 layers coextrudate properties (Example 4) Film properties before sterilization Values Total thickness 185 (microns) Interlayer adhesive strength (N/15 mm) PA/PE 17 PA/PP 15 Seal strength (N/15 mm) PE/PE 70 PP/PP 33 Tensile strength (MPa) MD TD 34.6/26.8 Yield strength (MPa) MD/TD 15.3/15.0 Elongation at break % MD/TD 490/430 1% secant modules (MPa) MD/TD 125/1 18 Coefficient of friction (COF) - static 0.32 Example 5 A fully coextruded 5 layers film A five layer structure (E D A C B) consisting of the same composition and thickness as in example 4 with the exception of layer A, which contains a modified PA consisting of a blend of 85% of polyamide-6 from EMS grade XE 3180 and 15% of PA 6I/6T from EMS grade Grivory G21 Film processing conditions Same as Example 4 with the exception of PA extruder (A) PA extruder (A) screw diameter 50 mm output 35 kg/hr RPM 56 Barrel temperature 235°C to 248°C Filter temperature 248°C Table 3: 5 layers coextrudate properties (Example 5) Film properties before sterilization Values Total thickness 183 (microns) Interlayer adhesive strength (N/15 mm) PA/PE 20 PA PP 16 Seal strength (N/15 mm) PE/PE 85 PP/PP 35 Tensile strength (MPa) MD/TD 36/34 Yield strength (MPa) MD/TD 14 5/14 8 Elongation at break % MD/TD 480/500 1% secant modulus (MPa) MD/TD 132/130 Coefficient of friction (COF) - static 0 34 Example 6 A 3 layers structure was prepared as follows: The outer layer (A) consists of 30 microns of a blend of 85% polyamide 6 from EMS , grade XE 3180 and 15% of polyamide 6I/6T from EMS, grade Grivory G21 . The inner layer (B) consists of 110 microns of C 8 LLDPE from DSM (Grade Stamylex 1026) additivated with 500 ppm Erucamide slip agent (1% masterbatch Polybatch slip FSU 105E). The adhesive layer (C) consists of 10 microns of maleic anhydride grafted LLDPE YPAREX 8104 E from DSM. Film processing conditions The line on which the structure was produced is the same as on Example 1; also the same processing conditions apply with the exception of J ) the polyamide extruder (C) . • Polyamide extruder (C) screw diameter. 70 mm output: 60 kg/hr. RPM: 30 Barrel temperature: 235°C to 255°C Filter temperature: 255°C. 2 > The die temperature is between 270°and 273°C Table 4 : semi coextrudate properties (Example 6) Film properties before sterilization Values Total thickness 148 (microns) Interlayer adhesive strength ( /15 mm) PA/PE 19 Seal strength (N/15 mm) PE/PE 72 Tensile strength (MPa) MD/TD 31/29.5 Yield strength (MPa) MD/TD 19/18 Elongation at break % MD/TD 480/505 1% secant modulus (MPa) MD/TD 132/124 Coefficient of friction (PE/PE) (COF) - static 0.32

Claims: CLAIMS 1) Cast-Coextruded multilayer film for sterilizable, low extractable containers of parenterai solutions, said film being: flexible and trasparent before and after steam sterilization, heatsealable to itself and/or to the parenterai solution container access ports, by its inner or outer layer; free from aromatic adhesives; incinerable without release of halogen containing fumes: and comprising at least a layer of olefin (co-) polymers and a layer of amide (co-) poiimer, characterized in that the film is made up of at least: A) an outer layer having a thickness of from 10-60 preferably 15 to50 microns and consisting of one or more polya ides (PA); B) an inner layer having a thickness of from 60 to 150 preferably from 80 to 130 microns, consisting of a linear low density (co-) polymer of ethylene (LLPDE) with a minor proportion from 0,5 to 10% of an alfa-olefin containing from to 12 carbon atoms, or of a blend of this (co-) polymer w th from 5 to 2 % of a low density polyethylene (LDPE), and containing from 0,1 - 3% of a slip agent; C) a polymeric adhesive intermediate layer having a thickness of from 3 to 20 microns and consisting of polyethylene (s) or ethylene copolymer with vinyl acetate (EVA), grafted with from 0,1 to 0,7% of maleic anhydride. 2) Coextruded multilayer film according to claim 1, characterized by two further layers (D) and (E) coextruded on the polyamide layer (PA), layer (D) having thickness of from 3 to 15 microns and consisting of low density polyethylene or polypropylene grafted with maleic anhydride, and layer E) having a thickness of 20 to 100 microns and consisting of a random propyiene copolymer with a diene, or of polyethylene. 3) Coextruded film according to claim 1, characterized by a further layer (E 1 ) wich consists of polyethylene or polypropylene, has a thickness of from 20 to 100 microns and is laminated on the polyamide layer (PA) with a polyurethane adhesive layer (D') having a thickness of from 2 to 10 micron. ) Bags in particular pouches formed of films according to the above claims, said pouches containing parenterai solutions, and being flexibles and transparent before and after sterilization.

Inventors: BUZIO PIER PAOLO, LAMBERT PHILIPPE, BUZIO, PIER, PAOLO, LAMBERT, PHILIPPE
Applicants: BIEFFE MEDITAL SA, BUZIO PIER PAOLO, LAMBERT PHILIPPE, BIEFFE MEDITAL S.A., BUZIO, PIER, PAOLO, LAMBERT, PHILIPPE
Application year: 1994
Main classification: B32B27
IPC codes: A61J1, B32B27